Interference-eliminating distributor cap vent means



F. S. SLICK July 19, 1960 I INTERFERENCE-ELIMINATING DISTRIBUTOR CAP VENT MEANS Filed May 7, 1957 INVENTOR. FRED 5. .SL IGK United. States Patent Ofiice 2,945,430 Patented July 19, 1960 INTERFERENCE-ELIMINATING DISTRIBUTOR CAP VENT MEANS Fred S. Slick, Ro'ckford, 11L, assignor, by mesne assignments, to said Slick and to Arthur C. Johnson and Chester A. Lender, all of Rockford, 111.

Filed May 7, 1957, Ser. No. 657,689

6 Claims. (Cl. 98--1) This relates to a vent means and especially to a vent used with distributor caps for magnetos for the purpose of dissipating gases and ventilating the interior of the magneto generally. This invention also relates to .a vent means that also grounds or absorbs electrical charges that may escape through the vent and interfere with the radio equipment of the aircraft or other vehicle.

Gases generated by the electrodes of a distributor are prone to oxidize the electrode surfaces and other metal components within the distributor, and a means of venting is'desirable in order to reduce the oxidizing action, prolong the life of the components and reduce the amount of servicing required.

The provision of a vent, however, may permit electrical charges, generated within the distributor, to escape and set up interference with radio equipment. The conventional vent is intended to permit air or gases to pass through it with the least possible resistance and to also prevent dust from being drawn into the distributor. Obviously, a vent that permits ventilation straight through without deflection is the most eflicient. In such a vent it is easy to filter dust from the air passing through. However, electrical charges also pass through this type of vent and it is an object of this invention to provide a vent means that absorbs electrical charges or grounds them so they do not escape to cause interference with radio equipment.

It is also an object of this invention to provide a means of ventilating a distributor that permits gases to escape and that allows air to breath through freely.

Another object of this invention is to provide a vent that can be easily replaced.

Further objects and advantages of the invention-will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawings wherein a satisfactory embodiment of the invention is shown. However, it is to be understood that the invention is not limited to the details disclosed but includes all such variations and modifications as fall within the spirit of the invention.

Referring to the drawing:

Fig. 1 is a fragmentary elevational view of the front cover of a distributor showing the vent forming the subject of this invention.

Fig. 2 is a fragmentary sectional view taken at 22 of Fig. 1 and showing the vent in position in the cover of the distributor.

Fig. 3 is an enlarged elevational front-end view of the vent removed from the cover.

Fig. 4 is a sectional view taken at 44 of Fig. 3, and showing the various components as assembled.

Fig. 5 is a sectional exploded view of the components of the vent before being assembled.

Referring to Figs. 1 and 2, is a cover of a distributor into which a vent 12, embracing this invention has been assembled. Cover 10: has a chamber 11 and encloses the conventional distributor components such as a rotor 14 which carries an electrode 16. Electrode 16 rotates, and in so doing passes into close proximity to stationary electrodes 18, only one of which is shown. The arc, resulting as electrode 16 passes an electrode 18, generates gases which if permitted to remain within the distributor cover 10 would seriously oxidize and corrode the electrodes and other metal components within the cover.

Vent 12 comprises a body 20 which in this instance is of aluminum and which is provided with an external thread fitting a corresponding tapped hole in cover 10. A hexagonal portion 22 provides a convenient means by which the body 20 can be assembled into the cover 10.

Body 20 has .two cylindrical recesses 24 and 26 machined, in the end thereof facing the inside of cover 10, leaving a wall 28. Recess 26 is of a larger diameter than recess 24 with the result that a ledge 30 results, to be used for a purpose to be later explained.

A group of vent holes 32 is drilled or otherwise provided in wall 28 as shown in Figs. 1, 3, 4 and 5. In this instance, 6 holes are provided and are located on a circle concentric with the axis of body 20. Holes 32 provide the means for gases to escape from cover 10, and for air to enter.

A cup-shaped screen or foraminated member 34 of aluminum screen wire in this instance, is shown in the assembly of Fig. 4 and in the exploded view of Fig. 5. It is fitted into recess 24 and has a flange 36 extending normally to the axis of body 20 and which when assembled in the latter, rests upon ledge 30. The cylindrical portion 38 of member 34 is preferably slightly smaller in diameter than that of recess, 24 to permit air and gases to have a greater venting and filtering area because the air and gases can pass between the portion 38 and the wall of recess 24, and edgewise through the filtering means as well as through the face 40 of member 34.

A porous pad or disk 42 of loosely pressed felt or other suitable filtering material is fitted closely into the cup portion of member 34 and should be of a thickness to extend flush with the upper surface of flange 36 or slightly higher.

A closing ring 44, of aluminum in this instance, is formed with a concave face toward the ledge 30 and is fitted closely in recess 26. Ring 44 has a cylindrical periphery before assembly for reasons which will appear. A hole 46 is provided centrally in ring 44 and is of a diameter less than the diametrical distance between the peripheries of holes 32, for reasons which will be explained.

When assembling the vent, the screen or foraminated member 34 is assembled in recess 24 with pad 42 resting in screen member 34. Closing ring 44 is placed in recess 26 and forced inwardly toward pad 42, compressing and expanding the latter as shown in Fig. 4. Edge 48 of ring 44 will embed itself into the periphery of recess 26, thereby effecting a seal and preventing ring 44 from becoming dislodged. Edge 50 of ring 44 becomes embeded into the surface of pad 42, forming a seal to prevent dust from by-passing around the periphery of pad 42. Contact between the face of ring 44 and the porous pad 42 is also effective as a further seal against dust by-passing the porous pad 42.

The operation of the vent 12 in absorbing electrical charges emanating in the distributor will now be explained:

Referring to Fig. 4, arrow 52 represents electrical charges emanating from the arcs passing across the gap, between electrodes 16 and 18. Any charges that strike ring 44, cover 10, or other metal components of the distributor will be grounded or absorbed. However, charges that pass through hole 46 will continue until they encounter face 40 of screen or foraminated member 34, or wall 28. Inasmuch, as electrical charges travel in straight paths they will not pass through holes 32, because the latter are located outwardly from the peripheryofhole 46. Consequently if some of the electrical chargesescape through the screen face 40, they will continue until they strike the inner face of wall 28 and be grounded to the frame of the distributor. It should be clearly understood that cover must be of metal, or provision made to otherwise ground vent 12 to the metal frame of the distributor.

Gases generated by the are occurring between electrodes 16v and 18 escape through vent holes 54, only one of which is shown. The others are uniformly spaced about the axis. of the molding 56, which also carries the bushing 58' that supports rotor shaft 60.

The above being a complete description of an illustrative. embodiment of the invention, What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A vent means, for an electrical device having an enclosure provided with an inner chamber and internally threaded aperture, the improvement comprising a cylindrical body threaded into said threaded aperture and having a first and a second cylindrical recess about the axis of said body facing said chamber, and defining an end wall, said second recess being of a diameter larger than said first recess resulting in a ledge at the juncture of said first and second recesses, a plurality of vent apertures being provided in said wall and spaced outwardly from said axis, a foraminated cup-shaped member fitted in said first recess of a diameter less than said recess, and having a flange resting on said ledge, a porous felt disk fitted in said cup-shaped member and a closing ring fitted into said second recess and having a central opening of a diameter less than the diametrical distance between said vent apertures, said ring being of concave form on the face thereof toward said disk and being pressed into place so that the circumferential edges of said opening compresses said porous disk and expands it into intimate contact with the periphery of said cup-shaped member and said face. I

2. A vent means, for an electrical device having an enclosure provided with an inner chamber and an aperture, the improvement comprising a cylindrical body fitted into said aperture and having first and second cylindrical recesses about the axis of said body and having an end wall adjacent said first recess, said second recess being of a diameter larger than said first recess resulting in a ledge between said first and second recesses, a plurality of vent apertures being provided in said wall and spaced from said axis, a foraminated cup-shaped member fitted in said first recess and having a flange resting on said ledge, a porous felt-like disk fitted in said cupshaped member, and a closing ring fitted into said second recess and having a central opening of a diameter less than the dia'metrical distance between said vent apertures, said ring being of concave form on the face thereof toward said disk and being pressed into place so that the circumferential edge of said opening is embedded into said porous disk and said disk is expanded normally to the axis of said cup-shaped member to contact the latter and said face.

3. A vent means, for an electrical device having an enclosure provided with a chamber, the improvement comprising a body secured in an opening in said enclosure and being provided with a cylindrical recess having a step, and opening into said chamber and defined outwardly of said chamber by a wall, a plurality of vent apertures being providedin said wall, offset axially and communicating with said recess, a foram'inated cupshaped member abutting said step, a porous matted disk fitted in said cup-shaped member and conforming thereto, and a closing ring fitted into said recess, having an axial opening and forced into said recess to compress said disk axially and expand it outwardly in said cupshaped member.

4. A vent means, for an electrical device having an enclosure provided with a chamber, the improvement comprising a body secured in an opening in said enclosure and having a cylindrical recess terminating in a wall and facing said chamber, said wall having an aperture spaced radially from the axis of said recess, a foraminated member in said recess co-extensive with the diameter thereof, a porous felted disk co-extensive withthe. diam: eter of said foraminated member and in contact therewith, and a disk fitted in said recess .to retain said porous disk in contact with said foraminated member and being provided with acentral hole.

5. A vent means, for an electrical device having an enclosure, the improvement characterized by a cylindrical body secured in an opening in said body and having a recess defined by an end wall, and provided With an aperture in said wall spaced radially from the axis of said body, a foraminated member co-extensive with the diameter of said recess, a porous felt disk adjacent said foraminated member and co-extensive with the diameter of said member and a ring in said recess to retain said disk in contact with said foraminated member, said ring having an openingof a diameter that will not overlap said aperture when projected axially.

6. In a vent means for an electrical device having an enclosing wall the combination with said wall of a body portion secured in said wall so as to be exposedonthe inner and outer surfaces thereof, said body portion pro-, viding an internal recess opening on one side of said wall and extending partly through said body portion to leave a part thereof providing an end wall for said recess, said recess having an enlarged portion extending from the open side of said recess along the length thereof and terminating short of said end wall so as to provide a ledge intermediate the end wall and said open side, a foraminated member seated on said ledge, a porous matted filter member seated on said foraminated member, and a closing member engaged with the margins of the enlarged portion of said recess and seated on said filter member, said closing member providing an opening therethrough having its margin seated on said filter member, and said end wall providing an opening therethrough which is axially offset from the first mentioned opening.

References Cited in the file of this patent UNITED STATES PATENTS 2,150,859 Gibson et al Mar. 14, 1939 2,780,705 Seigmeth Feb. 5, 1957 2,811,573 Williams Oct. 29, 1957 

